The present invention relates to a silver halide emulsion, a production method thereof, a silver halide light-sensitive photographic material and a silver halide light-sensitive color photographic material comprising the silver halide emulsion, and an image forming method utilizing them. Particularly, the present invention relates to a silver halide emulsion, which exhibits excellent development stability and excellent latent image stability at high intensity exposure, as well as excellent fine line reproduction stability, a silver halide emulsion, which exhibits high sensitivity as well as low fog at digital exposure which is performed for a short time at high irradiance, and exhibits excellent image stability during the period from completion of the exposure to the start of photographic processing, a production method thereof, a silver halide light-sensitive photographic material and a silver halide light-sensitive color photographic material comprising the silver halide emulsion, and image forming method utilizing them.
In recent years, silver halide color paper has been employed in a variety of places due to proliferation of minilabs. Along with such proliferation, exposures during printing have been carried out under various conditions as well as various circumstances. Further, on the market, problems have occurred in which development stability is degraded due to mixing of silver bleach solution with a color developing solution. Further, in recent years, digital image processing has increasingly progressed and the need has rapidly been increased for image formation by scanning exposure, employing high intensity light sources such as light emitting diodes and semiconductor lasers. As a result, an increase in suitability for high intensity and short time exposure is highly demanded for silver halide light-sensitive color photographic materials (hereinafter occasionally referred simply to as light-sensitive materials) employed as an image forming means. Specifically, it has been found that high intensity exposure results in increased susceptibility to effects due to processing solutions and increased degradation of latent image stability.
Namely, increasingly demanded are development of light-sensitive materials which result in excellent images based on conventional photographic image formation, as well as image formation employing quick scanning under high intensity light exposure.
At the same time, the progress of silver halide light-sensitive materials, which are advantageous for image quality, cost, and mass productivity, has been greatly sought in order to compete with the rapid progress of other non-silver salt output media such as ink jet printing systems.
Conventionally, as a means to achieve a quick development process, silver chloride emulsions or silver halide emulsions, having a high silver chloride content, have been employed.
On the other hand, Japanese Patent Application Open to Public Inspection No. 64-26837 discloses an emulsion having a high silver chloride content which has a portion of a high content of silver bromide near the apex of silver halide grains. Further, Japanese Patent Application Open to Public Inspection No. 1-105940 discloses that it is possible to provide an emulsion, having a high silver chloride content, in which silver bromide is subjected to localized Ir doping so as to achieve excellent latent image stability as well as to minimize failure of the reciprocity law. Still further, U.S. Pat. No. 5,627,020 discloses a method of forming the localized portions of silver bromide employing fine Ir doped silver bromide grains. However, none of the methods result in sufficient improvement in initial latent image stability after exposure. Further, Japanese Patent Application Open to Public Inspection No. 11-109534 describes a silver halide emulsion in which a phase having a higher silver bromide proportion, which comprises iridium compounds is located near the surface of silver halide grains and a region in which the concentration of iridium compounds is higher than the outside of said phase having a higher silver bromide proportion is prepared in the inside of said phase having a higher silver bromide proportion, so that failure of the reciprocity law as well as high humidity dependence is minimized and latent image stability is enhanced. These inventions are characterized in that a localized phase containing a high proportion of silver bromide, such as 10 to 40 percent, is provided at the apex portion of silver halide grains. However, the resulting stability of silver halide emulsions as well as the resulting processing stability are insufficient.
Still further, Japanese Patent Application Open to Public Inspection No. 2001-188311 discloses a method in which a phase having a higher proportion of silver bromide as well as silver iodide is provided and the introduction of said higher proportion phase is carried out twice independently, that is, prior to the addition of antifoggants and after the same so that the resulting failure of the reciprocity law is minimized and the resulting coating composition stability is enhanced. However, the stability of the resulting silver halide emulsion is insufficient.
Widely known as examples regarding doping of cyano ligand containing complexes are European Pat. Nos. 336,425 and 336,426; Japanese Patent Application Open to Public Inspection Nos. 2-20853, 2-20854, and 5-66511; U.S. Pat. Nos. 5,132,203, 4,847,191, and 3,790,300; and Japanese Patent Publication No. 48-35373. These patents exhibit an increase in sensitivity as well as minimization of failure of the reciprocity law, however drawbacks with latent image stability as well as minimization of fogging during photographic processing are not completely overcome. Further, Japanese Patent Application Open to Public Inspection Nos. 11-24194, 11-102042, 10-293377, 8-179452, and 7-72569 and U.S. Pat. Nos. 5,360,712, 5,457,021, and 5,462,849 describe an increase in sensitivity employing organic ligand complexes, comprising imidazole as a ligand. However, improvements are demanded due to insufficient development stability as well as insufficient latent image stability under high intensity exposure.
Further, it has been proved that in digital exposure systems which have recently received much attention, conventional techniques to improve latent image stability are not capable of resulting in commercially viable quality in the adaptability for high intensity exposure over a short time. Listed as techniques applied to such a digital exposure system are, for example, a chemical sensitization and spectral sensitization method suitable for formation of the localized silver bromide phase described in U.S. Pat. No. 5,601,513 and further methods employing iodochloride emulsions described in European Pat. Nos. 750,222 and 772,079.
However, according to investigations performed by the inventors of the present invention, it has been proved that when adaptability for digital exposure is improved employing the aforesaid techniques, latent image stability is not sufficiently enhanced, and in addition, pressure resistance as well as stability for temperature variation during exposure are markedly degraded. As a result, at present, development of improving technology is urgently demanded.
An aspect of the present invention is to provide a silver halide emulsion, which exhibits excellent development stability and excellent latent image stability at high intensity exposure, as well as excellent fine line reproduction stability. An other aspect of the present invention is to provide a silver halide emulsion, which exhibits high sensitivity as well as low fog at digital exposure which is performed for a short time at high irradiance, and exhibits excellent image stability during the period from completion of the exposure to the start of photographic processing. Still other aspect of the present invention is to provide a production method of the silver halide emulsion, a silver halide light-sensitive photographic material and a silver halide light-sensitive color photographic material comprising the silver halide emulsion, an d an image forming method utilizing them.
The aspects of the present invention were achieved employing the embodiments described below.
Structure 1
A silver halide emulsion contains silver chlorobromide grains or silver chloroiodobromide grains. Each of the silver halide grains has a silver chloride content of not less than 98% and comprises a silver bromide-containing layer having a silver bromide content of 0.5 to 5%, and the silver bromide-containing layer is located at a depth of 0 to 0.01 xcexcm from the surface of the grain.
Structure 2
A silver halide emulsion comprising silver halide grains containing Compound A having adsorptivity to silver. Each of the silver halide grains has a silver chloride content of not less than 90% and has a core-shell structure comprised of a core and shell having different contents of Compound A each other, and the content of Compound A in the shell is smaller than the content of Compound A in the core.
Structure 3
A silver halide emulsion comprising a silver halide grains, each of the silver halide grains having a silver chloride content of not less than 90%, prepared by being conducted a chemical sensitization,
wherein when the chemical sensitization is conducted, the Compound B having polychalcogen structure represented by the following General Formula (I), and a Mercapto Compound C are added in this order into a vessel, in which the chemical sensitization is conducted,
xe2x80x94(X)mxe2x80x94(Y)nxe2x80x94xe2x80x83xe2x80x83General Formula (I)
wherein each of X and Y represents an atom selected from sulfur, selenium and tellurium; each of m and n represents an integer of not less than 1.
Structure 4
An preparation method of a silver halide emulsion comprising silver halide grains comprising silver chlorobromide grains or silver chloroiodobromide grains. Each of the silver halide grains has a silver halide content of not less than 98%. The preparation method comprising the steps in the following order of: a host grain emulsion preparation step to prepare a host grain emulsion; a first bromide addition step to add a bromide compound to the host grain emulsion; a chemical sensitization step to subjecting a chemical sensitization to the host grain emulsion for at least 60 minutes after the first bromide addition step; and a second bromide addition step to add a bromide compound to the host grain emulsion after the chemical sensitization step.
Structure 5
A preparation method of a silver halide emulsion comprising silver halide grains, each of the silver halide grains having a silver chloride content of not less than 90%, the method comprising the steps in the following order of: preparing a host grain emulsion; adding a chemical sensitizer to the host grain emulsion; adding the Compound B having polychalcogen structure represented by the following General Formula (I); and adding the Mercapto Compound C.
Structure 6
A silver halide light-sensitive photographic material comprising a support provided thereon at least an image forming layer comprising the silver halide emulsion of the present invention.
Structure 7
A silver halide light-sensitive color photographic material comprising a support and provided thereon at least a yellow image forming layer, a magenta image forming layer and a cyan image forming layer, wherein at least one of the image forming layers comprises a silver halide emulsion of the present invention.
Structure 8
An image forming method comprising the steps of: exposing the silver halide light-sensitive color photographic material of claim 21 in an exposure time of 10xe2x88x9210 to 10xe2x88x923 second per pixel; and subjecting the silver halide light-sensitive color photographic material to color developing to obtain color images for the respective image forming layers, wherein the effective gradation range (VE) of each of the obtained color image is 0.65 to 0.84; and the difference (xcex94VE) between the VE value of the color image forming layer in which effective gradation range (VE) is maximized and the VE value of the color image forming layer in which effective gradation value (VE) is minimized is from 0 to 0.08.
The present invention will now be detailed.
In the present invention, it is preferable that in a silver halide emulsion comprising silver chlorobromide grains or silver chloroiodobromide grains having a silver chloride content of not less than 98 percent, each of the silver chlorobromide grains or silver chloroiodobromide grains has a layer having a silver bromide content of 0.5 to 5.0 percent, and the layer is located at a depth of 0 to 0.01 xcexcm from the surface of the silver halide grain. It is possible to form the silver bromide containing layer in the silver halide grain by adding fine silver halide grains having a silver bromide content of 0.5 to 5.0 percent, which have a smaller grain diameter than the host grain, namely preferably at most 0.1 xcexcm and more preferably at most 0.07 xcexcm. Further, it is preferable to adjust to 0.5 to 5.0 percent the silver bromide content of an aqueous halide solution which is added employing a double jet precipitation method known in the art in this industry. The silver bromide content of the finalized silver halide emulsion is preferably from 0.1 to 0.5 mol percent with respect to the total silver amount.
It was discovered that by uniformly providing the silver bromide-containing layer, having a silver bromide content of 0.5 to 5.0 percent, constituted as above, from grain surface to grain subsurface, it was possible to achieve compatibility between the processing stability and the latent image stability, and also to achieve excellent emulsion stability. It is preferable that said silver bromide containing layer has a silver bromide content of 2 to 4 percent.
Further, in the present invention, it preferable that in the silver halide emulsion comprising the silver chlorobromide grains or silver chloroiodobromide grains having a silver chloride content of at least 98 percent, each of the silver chlorobromide grains or silver chloroiodobromide grains has a region containing a complex having a cyano ligand at the position having a depth of 0.001 to 0.010 xcexcm from the silver halide grain surface, and has a region containing neither a complex having cyano ligand nor a complex having carbon atom at the position nearer the grain surface than the region containing the complex having the cyano ligand.
The complex having the cyano ligand according to the present invention are not particularly limited, as long as the complexes are coordinated with at least one cyano ligand. The complexes are preferred in which at least four cyano ligands are coordinated with iron, tellurium, and osmium. Specific examples of the complexes having cyano ligand usable in the present invention are shown below. However, the present invention is not limited to these examples.
A1: K4Fe(CN)6 
A2: K4Ru(CN)6 
A3: K4Os(CN)6 
In the present invention, it is preferable that in a silver halide emulsion comprising the silver chlorobromide grains or silver chloroiodobromide grains having a silver chloride content of at least 98 percent, each of the silver chlorobromide grains or silver chloroiodobromide grains has a region containing a complex having a carbon atom in the position at a depth of 0.001 to 0.010 xcexcm from the silver halide grain surface, and has a region containing neither a complex having a carbon atom nor a complex having cyano ligand at the position nearer the grain surface than the complex having a carbon atom.
The complex having a carbon atom according to the present invention refer to complexes, which are coordinated with at least one ligand having at least one carbon atom. The specific examples of compounds are shown below. However, the present invention is not limited to these examples.
B1: [Ru(byp)2(Sxe2x80x94NH3-phen)]2+
B2: Ru(acetylacetonate)3 
B3: [(NH3)5Ruxe2x80x94NCxe2x80x94C6H4xe2x80x94Cnxe2x80x94Ru (NH3)5](PF6)4 
B4: [RuCl2(byp)2]
Incidentally, abbreviations employed in the above compounds are as follows:
byp: bipyridine
phen: phenanthroline
In order to incorporate each complex compound of the present invention into the silver halide grain in the emulsion, the each complex may be added during the process prior to formation of silver halide grains, the silver halide grain forming process, or the physical ripening process after formation of silver halide grains, so that the constitution according to the present invention is achieved. In order to prepare silver halide emulsions which satisfy grain constituting conditions specified in the present invention, it is preferable that the complex compounds according to the present invention are dissolved with silver halides and are added during the grain forming process.
The added amount of the complex compounds of the present invention to silver halide grains is preferably from 1xc3x9710xe2x88x929 to 1xc3x9710xe2x88x922 mol per mol of silver halide, and is most preferably from 1xc3x9710xe2x88x928 to 5xc3x9710xe2x88x925 mol.
In order to prepare the silver halide emulsion of the present invention, heavy metal ions may further be incorporated in the interior of the grain. Listed as usable heavy metal ions may be each ion of Groups 8 through 10 metals such as iron, iridium, platinum, palladium, nickel, rhodium, osmium, ruthenium, and cobalt; Group 12 transition metals such as cadmium, zinc, and mercury; and others such as lead, rhenium, molybdenum, tungsten, gallium, and chromium. Further, complexes exhibiting desensitization, comprising a halogen ion, nitrosyl, or thionitrosyl incorporated in a ligand, may be employed in combination.
In the present invention, it is preferable that in a silver halide emulsion comprising silver chlorobromide grains or silver chloroiodobromide grains having a silver chloride content of at least 98 percent, during the grain preparation, a brominated compound is added at least twice and between the two addition steps, chemical sensitization is carried out for more than or equal to 60 minutes. It was discovered that by setting conditions as specified in the present invention, it was possible to achieve compatibility between the processing stability and the latent image stability, as well as to achieve the excellent emulsion stability.
The brominated compounds according to the present invention are not particularly limited, as long as they are bromides. They are preferably water-soluble compounds. For example, KBr, NaBr, AgBrCl, and AgBr are listed. These compounds are independently added at least twice. The interval of the two adding step is preferably after addition of sensitizer and before reaching the optimal point of chemical sensitization. During the interval, the chemical sensitization is carried out preferably for no less than 60 minutes and more preferably for no less than 120 minutes. Further, it is more preferable that in the presence of antifoggants, the first bromide addition is carried out. Further, it is preferable that antifoggants be added after the second bromide addition. Still further, it is preferable that antifoggants not be added during the second bromide addition.
Further, as a result of diligent investigations of the inventors of the present invention, it was discovered that one of the aspects of the present invention were achieved by employing chalcogen compounds and mercapto compounds during production of silver halide emulsions and optimizing the duration of addition time of each compound. Conventionally, during production of silver halide emulsions, chalcogen compounds and mercapto compounds have been widely employed as a sensitizer, an antifoggant and a development retarder. However, being based on conventional techniques, it is extremely difficult to assume that the embodiments of the present invention, in which the addition method as well as the added amount is taken into account, have achieved the aspect of the present invention. The results of the present invention are unexpected.
The silver halide emulsion of the present invention preferably has the following structures from the viewpoint of achieving the aspect of the present invention.
Namely, in the present invention, it is preferable that the silver halide emulsion has a silver chloride content of at least 90 percent, and the silver halide emulsion contains Compound A having adsorptivity to silver. Further, each of the silver halide grains of the silver halide emulsion has a core-shell structure comprising at least two regions having different concentration of said Compound A, and the concentration of said Compound A contained in the phase nearest the surface (hereinafter referred to as the shell region) is lower than the concentration of said Compound A contained in the deeper region from the surface (hereinafter referred to as the core region). It is particularly preferable that the average concentration of Compound A contained in the shell region is less than 1.5xc3x9710xe2x88x924 mol per mol of silver halide.
Further, as another embodiment, it is preferable that the silver halide emulsion has a silver chloride content of at least 90 percent, and the silver halide emulsion is prepared by subjected to a chemical sensitization, and when the chemical sensitization is conducted, the Compound B having polychalcogen structure represented by the following General Formula (I), and a Mercapto Compound C are added in this order into a vessel, in which the chemical sensitization is conducted. This like silver halide emulsion can be prepared by adding Compound B having the structure represented by aforesaid General Formula (I) and Mercapto Compound C in the stated order during chemical sensitization process of said silver halide emulsion.
Specifically, in the production method, it is preferable that in the chemical sensitization, the Compound B is added 120 minutes after the addition of a chemical sensitizer, and the Mercapto Compound C is added later than that. Further, it is preferable that the interval between addition of Compound B and addition of Mercapto Compound C is from 10 seconds to 30 minutes. Still further, it is particularly preferable that Compound B has a sulfur containing ring structure.
By employing these production methods, it is possible to prepare silver halide emulsions, especially when subjected to digital exposure, which exhibit higher sensitivity, lower fogging, excellent latent image stability, and enhanced pressure resistance.
The composition of silver halide emulsions other than those described above and the composition elements of silver halide light-sensitive color photographic materials will now be detailed.
The silver halide emulsion according to the present invention (hereinafter referred to as the emulsion of the present invention) is characterized to be a so-called high silver chloride emulsion having a high silver chloride content. A high silver chloride emulsion, which is comprised of silver chloride in an amount of at least 90 mol percent, is preferred. In such a case, the emulsion may have optimal compositions such as silver chloride, silver chlorobromide, silver chloroiodobromide, and silver chloroiodide. However, silver chlorobromide and silver chloroiodide comprising silver chloride in an amount of 97 mol percent are specifically preferred. From the viewpoint of quick processing characteristics as well as processing stability, a silver halide emulsion comprising silver chloride in an amount of no less than 98 mol percent is more preferred and 98.0 to 99.9 mol percent is still more preferred.
In the present invention, it is preferable that the silver halide grains of the silver halide emulsion are formed in the presence of Compound A having adsorptivity to silver. The Compound A having adsorptivity to silver in the present invention, refers to compounds capable of forming salts with silver ions, which exhibit the desired low solubility. The solubility product of silver salts is commonly represented by a pKsp value. Compound A of the present invention refers to that the salt of Compound A and silver ion has pKsp value of 10 to 18. Specifically listed as compounds which exhibit such a value are compounds having a mercapto group and nitrogen containing heterocyclic compounds such as tetraazaindenes, tetrazoles, benzimidazoles, benzotriazoles, and imidazoles. Of these, compounds having a mercapto group are p referred and compounds having a mercaptotetrazole structure are more preferred.
Listed as examples of preferred Compound A which can be used to achieve this purpose may be compounds represented by following General Formula (II) described in the lower column on page 7 of Japanese Patent Application Open to Public Inspection No. 2-146036. 
Listed as specific examples of more preferred Compound A may be following compounds (IIa-1) through (IIa-8) and (IIb-1) through (IIb-7) described on page 8 of the aforesaid patent publication. 
Further, compounds such as 1-(3-methoxyphenyl)-5-mercaptotetrazole and 1-(4-ethoxyphenyl)-5-mercaptotetrazole can be cited as preferable examples of Compound A. However, the present invention is not limited to these examples.
The silver halide grain in the emulsion of the present invention preferably comprises at least two regions in which the concentration of aforesaid Compound A is different from each other. It is more preferable that the concentration of Compound A contained in a surface region (a shell region) is less than the concentration of Compound A contained in the interior region (the core region). The shell region, as described herein, refers to the final region during grain formation through grain growth and the exterior region of the grain including the grain surface. In the present invention, the entire region of the grain interior from this shell region is defined as the core region. The number of the region in which the concentration of Compound A is different is not particularly limited. Further, the concentration of Compound A is also not limited as long as desired grains are formed. However, in the present invention, it is preferable that the concentration of Compound A in the shell portion is less than the concentration of Compound A in the core portion.
Further, the average concentration of Compound A in the shell region of the silver halide grain of the present invention is preferably less than 1.5xc3x9710xe2x88x924 mol per mol of silver halide. The concentration of Compound A incorporated in the shell may be 0, is preferably from 0.1 to 1xc3x9710xe2x88x924 mol per mol of silver halide, and is more preferably from 0.1 to 0.5xc3x9710xe2x88x924 mol.
The concentration of Compound A contained in the core region is not limited as long as it is greater than that in the shell region, but is preferably from 0.5 to 3xc3x9710xe2x88x924 mol.
Further, a plurality of compounds may be added in combination, as long as the compounds correspond to Compound A, and types of the compounds as well as combinations of the compounds in the core region may be different from those in the shell region. As long as the total amount of added compounds satisfies the conditions specified in the present invention, the effects of the present invention will be sufficiently exhibited. These compounds may be incorporated in the system, in which grains are formed, employing any method. However, it is preferable that these compounds are previously incorporated in a halide solution and subsequently added.
In the production method of the silver halide emulsion of the present invention, the volume of the shell region is preferably within 50 percent of the total volume of silver halide grains, and is more preferably within 30 percent. Further, it is preferable to apply the present invention to the embodiments in which a sub-surface region near the surface, which is extremely shallow, is employed as a shell region.
The silver halide grains in the silver halide emulsion of the present invention preferably comprises Compound B having the polychalcogen structure represented by aforesaid General Formula (I) in the core region, and Mercapto Compound C in the shell region.
In aforesaid General Formula (I), X and Y each represents an atom selected from sulfur, selenium, or tellurium, and m and n each represents an integer of 1 or more. Atoms X and Y may be linked by a single bond or an unsaturated bond.
Compounds which comprise the aforesaid structure are included in Compound B according to the present invention. However, compounds, having a polysulfide structure are preferred in which both X and Y represent a sulfur. One of such preferred compounds is a disulfide compound.
Further, more preferred Compound B includes compounds having such a structure that the aforesaid polysulfide structure is included in a ring structure. Listed as one of the most preferred compounds is elemental sulfur.
Specific compounds represented by Compound B usable in the present invention will now be exemplified. However, the present invention is not limited to these examples. Further, as long as compounds correspond to Compound B, these may be employed in combinations of a plurality of them. 
Mercapto Compound C according to the present invention corresponds to representative compounds which are generally employed as an antifoggant. Listed as examples of preferred compounds usable for this purpose may be the compounds represented by General Formula (II) described above. Listed as more preferred compounds may be compounds (IIa-1) through (IIa-8) and (IIb-1) through (IIb-7) described above, and 1-(3-methoxyphenyl)-5-mercaptotetrazole and 1-(4-ethoxyphenyl)-5-mercaptotetrazole. However, the present invention is not limited to these examples.
In the production method of the silver halide emulsion of the present invention, it is preferable that during chemical sensitization process, the aforesaid Compound B is added and subsequently, the aforesaid Mercapto Compound C is added. When each of the aforesaid compounds is simultaneously added, the aforesaid compounds are previously mixed and then added, or Compound B is added after adding Mercapto Compound C, it is difficult to exhibit the effects of the present invention.
Each of the aforesaid Compounds B and C according to the present invention may be added at any time during the chemical sensitization process of silver halide emulsions. However, it is preferable that addition is carried out at the stage in which the chemical sensitization has progressed sufficiently. Specifically, it is preferable that the aforesaid compounds are added 120 minutes after the addition of chemical sensitizers. Further, it is preferable that the interval between addition of Compound B and addition of Mercapto Compound C is from 10 seconds to 30 minutes. Specifically, it is preferable that Mercapto Compound C is added from 5 to 20 minutes after adding Compound B. In such a case, the added amount of Compound B is preferably from 5xc3x9710xe2x88x928 to 1xc3x9710xe2x88x926 mol per mol of silver halide. Further, the added amount of Mercapto Compound C is preferably from 1xc3x9710xe2x88x925 to 5xc3x9710xe2x88x923 mol per mol of silver halide.
In the present invention, the image forming method preferably comprises a step of: exposing a silver halide light-sensitive color photographic material in an exposure time of 10xe2x88x9210 to 10xe2x88x923 second per pixel; and subjecting the exposed silver halide light-sensitive color photographic material to color developing. The silver halide light-sensitive color photographic material comprises a support having thereon at least one each of a yellow image forming layer, a magenta image forming layer, and a cyan image forming layer, at least one layer of said color image forming layers comprising the silver halide emulsion of the present invention. Further, it is preferable that the effective gradation range (VE) of a color image obtained by color developing is from 0.65 to 0.84 for each of the color image forming layers, and the difference (xcex94VE) between the VE value of the color image forming layer in which effective gradation range (VE) is maximized and the VE value in which effective gradation value (VE) is minimized is from 0 to 0.08.
The effective gradation range (VE), as described in the present invention, is defined as the exposure amount range in which the point-gamma value during output of a gray scale becomes not less than 1.0. The inventors of the present invention performed diligent investigations and discovered that said exposure range resulted in great effects on print image quality during digital exposure, and particularly great effects on reduced bleeding of text images as well as reduced occurrence of scanning exposure streaks.
Incidentally, the point-gamma, as described in the present invention, is defined by the following formula which is described in xe2x80x9cThe Theory of the Photographic Processxe2x80x9d, edited by T. H. James, Fourth Edition, page 502, and represents the differential value of an optional point on the characteristic curve (D-LogE curve) comprised of ordinate-density D and abscissa-exposure amount:
xe2x80x83Point-gamma=dD/dLogE
wherein D represents the density and E represent the exposure amount.
In the image forming method of the present invention, from the viewpoint of achieving the target effects of the present invention, it is preferable to satisfy necessary conditions specified in the present invention, employing exposure conditions, such as an exposure time of 10xe2x88x9210 to 10xe2x88x923 second per pixel. In order to further clarify the effects of the present invention, it is possible to preferably employ the evaluation methods described below.
Namely, a 1 cm square patch is exposed to a light-sensitive material under variation of the exposure amount, employing a laser scanning exposure apparatus which is adjusted so that overlapping between rasters of the light beam is in the range of 5 to 30 percent. The exposed light-sensitive material is subjected to color development (incidentally, after color development, conventional bleach-fixing and washing or stabilization process are carried out) at 37xc2x10.5xc2x0 C. for 45 seconds, employing color developing solution (CDC-1), described below. Subsequently, the reflection density of gray patch portions of the resulting sample is determined, and a characteristic curve is drawn in which the abscissa represents the exposure amount (LogE) and the ordinate represents the reflection density (D). At each step, the differential value of density with respect to the exposure amount is calculated, whereby it is possible to determine the point-gamma. Incidentally, time from the completion of exposure to the start of development should be one hour.
(Color Developing Solution (CDC-1))
Pure water 800 ml
Triethylenediamine 2g
Diethylene glycol 10 g
Potassium bromide 0.02 g
Potassium chloride 4.5 g
Potassium sulfite 0.25 g
N-ethyl-N-(xcex2methanesulfonamidoethyl)-3-methyl-4-aminoaniline sulfate 4.0 g
N,N-diethylhydroxylamine 5.6 g
Triethanolamine 10.0 g
Sodium diethylenetriaminepentaacetato 2.0 g
Potassium carbonate 30 g
Water to make 1 liter
The pH was adjusted to 10.1 by adding sulfuric acid or potassium hydroxide.
In the present invention, the diameter of a light beam (the beam diameter) is identified as raster width. The light beam diameter, as described herein, can be defined as the diameter of a circle which is formed by taking out the point so that the intensity of said light beam becomes exe2x88x922 times the maximum intensity (the beam center). It is possible to determine the light beam diameter employing, for example, a beam monitor in which a slit and a power merger are combined.
The composition of silver halide emulsions other than those described above and the composition elements of silver halide light-sensitive color photographic materials will now be detailed.
Heavy metal ions are preferably incorporated in the silver halide emulsions of the present invention. Listed as preferably usable heavy metal ions to achieve such objects, may be each ion of Group 8 through 10 metals such as iron, iridium, platinum, palladium, nickel, rhodium, osmium, ruthenium, and cobalt; Group 12 transition metals such as cadmium, zinc, and mercury; and other metals such as lead, rhenium, molybdenum, tungsten, gallium, and chromium. Of these, preferred are metal ions of iron, iridium, platinum, ruthenium, gallium, and osmium. These metal ions may be added to silver halide emulsions in the form of salts and complexes.
When the aforesaid heavy metal ion forms a complex, preferred as ligands or ions are, for example, cyanide ions, thiocyanate ions, cyanate ions, chloride ions, bromide ions, iodide ions, nitrate ions, carbonyl and ammonia. Of these, preferred are cyanide ions, thiocyanate ions, isothiocyanate ions, chloride ions, and bromide ions.
Heavy metal ions may be incorporated in the silver halide emulsion of the present invention as follows. Any of said heavy metal compounds may be added at any time prior to formation of silver halide grains, during formation of silver halide grains, and during physical ripening after formation of silver halide grains. In order to prepare silver halide emulsions which satisfy the aforesaid conditions, it is possible to dissolve heavy metal compounds together with halide salts and continuously add the resulting solution over the entire period of the grain formation process or during a part of the process.
The added amount of the aforesaid metal ions in a silver halide emulsion is preferably from 1xc3x9710xe2x88x929 to 1xc3x9710xe2x88x922 mol per mol of silver halide, and is more preferably from 1xc3x9710xe2x88x928 to 5xc3x9710xe2x88x925 mol.
The silver halide emulsion of the present invention may be prepared employing the acid method, the neutral method, or the ammonia method. Further, silver halide grains may be those which are grown without any treatment or which are grown after preparing seed grains. The method to prepare seed grains may be the same as or different from the method to grow full-sized grains.
Further, employed as methods to allow water-soluble silver salts to react with water-soluble halides may be a normal mixing method, a reverse mixing method, a double-jet method, and combinations thereof. Of these, the double-jet method is preferred. Further, employed as one method of the double-jet method may be a pAg controlled double jet method, described in Japanese Patent Publication Open to Public Inspection No. 54-48521.
Still further, employed may be an apparatus, described in Japanese Patent Publication Open to Public Inspection Nos. 57-92523 and 57-92524, in which water-soluble silver salts, as well as water-soluble halides, are supplied from an addition apparatus arranged in a reaction mother composition, an apparatus, described in German OLS Pat. No. 2,921,164, in which an aqueous water-soluble silver salt solution, as well as an aqueous water-soluble halide solution, is added while continuously varying the concentration, and an apparatus, described in Japanese Patent Publication No. 5-6-501776, in which a reaction mother composition is removed from a reaction vessel and grains are formed while maintaining a constant distance among silver halide grains by concentrating said reaction mother composition, employing an ultrafiltration method. Further, if desired, silver halide solvents such as thioether may be used. Still further, compounds such as mercapto group containing compounds, nitrogen containing heterocyclic compounds and compounds such as sensitizing dyes may be added during formation of silver halide grains, or after the completion of grain formation.
In the light-sensitive materials of the present invention, it is possible to employ silver halide grains having any of several optional shapes. One of preferred examples is a cube having a (100) plane as a crystal surface. Further, grains having a shape such as an octahedron, a tetradecahedron, or a dodecahedron are prepared, employing methods described in publications such as U.S. Pat. Nos. 4,183,756 and 4,225,666; Japanese Patent Application Open to Public Inspection No. 55-26589; Japanese Patent Publication No. 55-42737, and Journal of Photographic Science 21, 39 (1973), and employed. Still further, grains having a twin plane may be employed.
In the present invention, it is preferable that at least 50 percent of the total projected area of said silver halide grains in the silver halide emulsion is comprised of planar particles having an aspect ratio of at least 2.
In the light-sensitive materials of the present invention, silver halide grains, which are comprised of a single shape, are preferably employed. However, it is particularly preferable that at least two types of monodispersed silver halide emulsions are added to the same layer.
The diameter of silver halide grains of the present invention is not particularly limited. However, taking into account quick processing properties, sensitivity, and the other desirable photographic performance, the diameter is preferably in the range of 0.1 to 1.2 xcexcm, and is more preferably in the range of 0.2 to 1.0 xcexcm. It is possible to determine said diameter, employing the projected area of grains or a diameter approximated value. When grains have a substantially uniform shape, it is possible to express the resulting grain size distribution, employing the diameter or the projected area.
Silver halide grains employed in the light-sensitive materials of the present invention are preferably monodispersed silver halide grains of which grain size distribution has a variation coefficient of preferably at most 0.22 and more preferably at most 0.15. It is particularly preferable that at least two types of monodispersed emulsions, having a variation coefficient of at most 0.15, a re added to the same layer. The variation coefficient, as described herein, refers to a coefficient representing the width of the grain size distribution and is defined by the formula described below:
Variation coefficient=S/R
wherein S is the standard deviation of the grain size distribution and R is the average grain diameter.
As used herein, th e grain diameter refers to the diameter when a silver halide grain is spherical, and to the diameter of a circle having the same area as the projected image when a silver grain is cubic or in a shape other than a sphere.
Employed as apparatuses and methods to prepare silver halide emulsions may be any of those known in the art of this industry.
Further, employed may be an apparatus, described in Japanese Patent Publication Open to Public Inspection Nos. 57-92523 and 57-92524, in which water-soluble silver salts, as well as water-soluble halides, are supplied from an addition apparatus arranged in a reaction mother composition, an apparatus, described in German OLS Pat. No. 2,921,164, in which an aqueous water-soluble silver salt solution, as well as an aqueous water-soluble halide solution, is added while continuously varying the concentration, and an apparatus, described in Japanese Patent Publication No. 56-501776, in which a reaction mother composition is removed from a reaction vessel and grains are formed while maintaining a constant distance among silver halide grains by concentrating said reaction mother composition, employing an ultrafiltration method. Further, if desired, silver halide solvents such as thioether may be used. Still further, compounds such as mercapto group-containing compounds, nitrogen-containing heterocyclic compounds and compounds such as sensitizing dyes may be added during formation of silver halide grains, or after the completion of grain formation.
In the present invention, it is preferable that silver halide grains undergo gold sensitization. It is possible to employ combinations of a sensitizing method employing chalcogen sensitizers with the gold sensitizing method. Employed as chalcogen sensitizers usable in silver halide emulsions may be, for example, sulfur sensitizers, selenium sensitizers, and tellurium sensitizers, and of these, sulfur sensitizers are preferred. Listed as sulfur sensitizers are, for example, thiosulfates, allylthiocarbamidothiourea, allylisothiacyantes, cystine, p-toluenethiosulfonate, rhodanine, and inorganic sulfur. It is preferable to vary the added amount of sulfur sensitizers, depending on the types of silver halides emulsions, as well as the magnitude of desired effects. However the added amount is in the range of about 5xc3x9710xe2x88x9210 to about 5xc3x9710xe2x88x925 mol per mol of silver halide, and is preferably in the range of 5xc3x9710xe2x88x928 to 3xc3x9710xe2x88x925 mol.
Added as gold sensitizers may be, for example, chloroauric acid, gold sulfide and various other gold complexes. Listed as usable ligand compounds may be, for example, dimethylrhodanine, thiocyanic acid, mercaptotetrazol, and mercaptotriazole. Further, preferred are gold sensitizers comprised of sensitizing components such as sulfur and selenium, and gold sensitizers having a group which forms silver sulfide or silver selenide.
The used amount of the aforesaid gold compounds varies depending on the kinds of silver halide emulsions, the types of used compounds, and ripening conditions, however, is preferably from 1xc3x9710xe2x88x924 to 1xc3x9710xe2x88x928, with more preferred amounts being from 1xc3x9710xe2x88x925 to 1xc3x9710xe2x88x928. Employed as chemical sensitizing methods of silver halide emulsions according to the present invention may be a reduction sensitizing method.
For the purpose of minimizing fog formed during preparation processes of light-sensitive materials, performance variation during storage, and fog formed during development, antifoggants as well as stabilizers, known in the art, may be incorporated in silver halide emulsions used to prepare light-sensitive materials of the present invention. Listed as examples of compounds which are employed to achieve the aforesaid purpose may be compounds represented by General Formula (II) described above. Further listed as more preferable specific compounds may be compounds (IIa-1) through (IIa-8) and (IIb-1) through (IIb-7) described above and compounds such as 1-(3-methoxyphenyl)-5-mercaptotetrazole and 1-(4-ethoxyphenyl-5-mercaptotetrazole. Based on the purposes, these compounds are added during any of the processes for preparing silver halide emulsion grains, and the chemical sensitization process, at the completion of the chemical sensitization process and the process for preparing coating composition. When chemical sensitization is performed in the presence of these compounds, they are preferably employed in an amount of about 1xc3x9710xe2x88x925 to about 5xc3x9710xe2x88x924 mol per mol of silver halide. When added at the completion of chemical sensitization, the added amount is preferably from about 1xc3x9710xe2x88x926 to about 1xc3x9710xe2x88x922 mol per mol of silver halide, and is more preferably from 1xc3x9710xe2x88x925 to 1xc3x9710xe2x88x923 mol. When added to a silver halide emulsion layer during process for preparing coating compositions, the added amount is preferably from about 1xc3x9710xe2x88x926 to about 1xc3x9710xe2x88x921, with the more preferred amount being from 1xc3x9710xe2x88x925 to 1xc3x9710xe2x88x922 mol. Further, when added to constitution layers other than silver halide emulsion layers, the amount is preferable so as to result in a coating of about 1xc3x9710xe2x88x929 to about 1xc3x9710xe2x88x923 mol per m2.
For the purpose of minimizing irradiation as well as halation, dyes which absorb various wavelength regions may be employed in the light-sensitive materials of the present invention. For said purpose, any of the compounds known in the art may be employed. Preferably employed as dyes having absorption in the visible region are dyes AI-1 through -11 described on page 308 of Japanese Patent Application Open to Public Inspection No. 3-251840, dyes described in Japanese Patent Application Open to Public Inspection No. 6-3770, and dyes described in Japanese Patent Application Open to Public Inspection No. 11-119379. Preferred as infrared radiation absorbing dyes, are compounds represented by General Formula (I), (II), and (III) described in the lower left column on page 2 of Japanese Patent Application Open to Public Inspection No. 1-280750, which have preferred spectral characteristics, exhibit no adverse effects for photographic characteristics of silver halide photographic emulsions, and result in no staining due to residual color. Listed as specific examples of preferable compounds may be exemplified compounds (1) through (45) cited from the lower left column on page 3 to the lower left column on page 5 of the aforesaid patent publication. When these dyes are employed to improve sharpness, the preferable added amount is such that the spectral reflection density of unprocessed light-sensitive materials is at least 0.7 at 680 nm, and the more preferable added amount is that the same is at least 0.8.
Optical brightening agents are preferably incorporated in the light-sensitive materials of the present invention to improve background whiteness. Listed as preferably employed compounds are those represented by General Formal II described in Japanese Patent Application Open to Public Inspection No. 2-232652.
The silver halide light-sensitive color photographic materials of the present invention have layers comprising silver halide emulsions which are spectrally sensitized to the specified wavelength region of 400 to 900 nm, in combination with yellow couplers, magenta couplers and cyan couplers. Said silver halide emulsion comprises one type of a sensitizing dye or a combination of at least two types of sensitizing dyes.
Employed as spectral sensitizing dyes usable in the silver halide emulsions of the present invention are any of the several compounds known in the art. As blue-sensitive sensitizing dyes, BS-1 through -8, described on page 28 of Japanese Patent Application Open to Public Inspection No. 3-251840, may preferably be employed individually or in combination. Preferably employed as green-sensitive sensitizing dyes may be GS-1 through GS-5 described on page 28 of the aforesaid patent publication. Preferably employed as red-sensitive sensitizing dyes may be RS-1 through RS-8 described on page 29 of the aforesaid patent publication. When image exposure is carried out employing infrared radiation while utilizing a semiconductor laser, it is required to employ infrared-sensitive dyes. Preferably employed as infrared-sensitive sensitizing dyes are IRS-1 through IRS-11 described on pages 6 through 8 of Japanese Patent Application Open to Public Inspection No. 4-285950. Further, it is preferable that supersensitizers SS-1 through SS-9, described on pages 8 and 9 of Japanese Patent Application Open to Public Inspection No. 4-285950, or compounds S-1 through S-17, described on pages 15 through 17 of Japanese Patent Application Open to Public Inspection No. 5-66515, are employed while combined with these infrared-, red-, green-, and blue-sensitive sensitizing dyes. Each of these sensitizing dyes may be added at any time from the formation of silver halide grains to the completion of chemical sensitization.
Sensitizing dyes may be dissolved in water-compatible organic solvents such as methanol, ethanol, fluorinated alcohol, acetone, and dimethylformamide or water, and the resulting solution may be added. Alternatively, sensitizing dyes may be subject ed to solid dispersion followed by addition.
Employed as couplers employed in the silver halide light-sensitive color photographic materials of the present invention may be any compounds capable of forming coupling products having a maximum spectral absorption wavelengths in the longer wavelength region of more than 340 nm by undergoing coupling reaction with the oxidation product of a color developing agent. Specifically, representative compounds include yellow dye forming couplers having a maximum spectral absorption wavelength in the region of 350 to 500 nm, magenta dye forming couplers having a maximum spectral absorption wavelength in the region of 500 to 600 nm, and cyan dye forming couplers having a maximum spectral absorption wavelength in the region of 600 to 750 nm.
Listed as cyan couplers preferably usable in the silver halide light-sensitive color photographic materials of the present invention may be the couplers represented by General Formulas (C-I) and (C-II) described in the lower left column on page 5 of Japanese Patent Application Open to Public Inspection No. 4-114154. Listed as specific compounds may be those described as CC-1 through CC-9 from the lower right column on page 5 to the lower left column on page 6 of the aforesaid patent publication.
Listed as magenta couplers preferably usable in the silver halide light-sensitive color photographic materials of the present invention may be the couplers represented by General Formulas (M-I) and (M-II) described in the upper right column on page 4 of Japanese Patent Application Open to Public Inspection No. 4-114154. Listed as specific compounds may be those described as MC-1 through MC-11 from the lower left column on page 4 to the lower right column on page 5 of the aforesaid patent publication. Of the aforesaid magenta couplers, more preferred are the couplers represented by General Formula (M-I) described in the upper right column on page 4 of the aforesaid patent publication. Of these, particularly preferred are the couplers, in which RM of aforesaid General Formula (M-I) is a tertiary alkyl group, since excellent lightfastness is obtained. MC-8 to MC-11 described in upper column on page 5 of the aforesaid patent publication are preferred since those result in excellent color reproduction from blue to violent and red, as well as detailed reproduction.
Listed as yellow couplers preferably usable in the silver halide light-sensitive color photographic materials of the present invention may be the couplers represented by General Formula (Y-I) described in the upper right column on page 3 of Japanese Patent Application Open to Public Inspection No. 4-114154. Listed as specific compounds may be those described as YC-1 through YC-9 from the lower left column on page 3 to the following of the aforesaid patent publication. Of the aforesaid yellow couplers, preferred are couplers in which RY1 in General Formula [Y-I] described in the aforesaid patent publication is an alkoxy coupler, or couplers represented by General Formula [I] described in Japanese Patent Application Open to Public Inspection No. 4-114154, since these are capable of reproducing yellow having preferred tints. Of these, particularly preferred are YC-8 and YC-9 described in the lower left column on page 4 of the aforesaid patent publication, as well as compounds represented by No. (1) through (47) described on pages 13 and 14 of Japanese Patent Application Open to Public Inspection No. 6-67388. Further, the most preferred compounds are those represented by [Y-1] described on page 1 and pages 11 through 17 of Japanese Patent Application Open to Public Inspection No. 4-81847.
Herein, described are addition methods of couplers as well as other organic compounds used in silver halide light-sensitive color photographic materials of the present invention. As one of the methods, when an oil-in-water type emulsification dispersion method is employed, the aforesaid couplers as well as organic compounds are dissolved in water-insoluble high-boiling point organic solvents, commonly having a boiling point of at least 150xc2x0 C., if desired together with low-boiling point and/or water-soluble organic solvents, and the resulting mixture is subjected to emulsification dispersion into hydrophilic binders, such as an aqueous gelatin solution, employing surface active agents. Employed as dispersion means may be stirrers, homogenizers, colloid mills, flow jet mixers, and ultrasonic homogenizers. A process which removes low-boiling point organic solvents may be provided after dispersing or simultaneously during dispersion. Preferably employed as high-boiling point organic solvents usable for dissolving and dispersing couplers are, for example, phthalic acid esters such as dioctyl phthalate, diisodecyl phthalate, and dibutyl phthalate, phosphoric acid esters such as tricresyl phosphate and trioctyl phthalate, and alcohols. The dielectric constant of high-boiling point organic solvents is preferably from 3.5 to 7.0. Further, at least two types of high-boiling point organic solvents may be employed in combination.
On the other hand, instead of the aforesaid method, or while employed in combination with high-boiling point organic solvents, a method may be employed in which water-insoluble and organic solvent-soluble polymers are dissolved, if desired, in low-boiling point and/or water-soluble organic solvents, and subsequently, emulsification dispersion into hydrophilic binders such as an aqueous gelatin solution, is carried out employing various dispersion means. Listed as water-insoluble and organic solvent-soluble polymers employed for the above method may be poly(N-t-butylacrylamide).
Listed as preferred compounds as a surface active agent, which are employed to control surface tension during dispersion of photographic additives or during coating, are those having in a single molecule a hydrophobic group having from 8 to 30 cation atoms as well as a sulfonic acid group or salts thereof. Specifically listed are compounds A-1 through A-11 described in Japanese Patent Publication Open to Public Inspection No. 64-26854. Further, preferably employed are surface active agents in which the alkyl group is substituted with fluorine atom(s). These dispersions are commonly added to coating compositions comprising silver halide emulsions. The shorter the time until the addition to the coating composition after dispersion and the time until coating after the addition to the coating composition, the better. Each of these is preferably within 10 hours, is more preferably within three hours, and is still more preferably within 20 minutes.
In order to minimize fading of formed dye images due to light, heat and humidity, it is preferable that antifading agents are employed in combination. Particularly preferred compounds include phenyl ether based compounds represented by General Formulas I and II described on page 3 of Japanese Patent Publication Open to Public Inspection No. 2-66541, phenol based compounds represented by General formula IIB described in Japanese Patent Publication Open to Public Inspection No. 3174150, amine based compounds represented by General Formula A described in Japanese Patent Publication Open to Public Inspection No. 65-90445, and metal complexes represented by General Formulas XII, XIII, XIV, and XV described in Japanese Patent Publication Open to Public Inspection No. 62-182741, which are particularly preferable for magenta dyes. Further, the compounds represented by General Formula Ixe2x80x2 described in Japanese Patent Publication Open to Public Inspection No. 1-196049, as well as the compounds represented by General Formula described in Japanese Patent Publication Open to Public Inspection No. 5-11417 are particularly preferred for yellow and cyan dyes.
For the purpose of shifting the absorption wavelengths of dyes formed by color development, it is possible to use compound (d-11) described in the lower left column on page 9 of Japanese Patent Publication Open to Public Inspection No. 4-114154, and compound (Axe2x80x2-1) described in the lower left column on page 10 of the aforesaid patent publication. Other than these, it is possible to use fluorescent dye releasing compounds described in U.S. Pat. No. 4,774,187.
In the silver halide light-sensitive color photographic materials of the present invention, it is preferable that color contamination is minimized by adding compounds which react with the oxidation products of developing agents to the layer between light-sensitive layers, or fog is minimized by adding those to silver halide containing layers. Preferably employed as compounds for these purposes are hydroquinone derivatives. More preferred compounds include dialkylhydroquinones such as 2,5-t-octylhydroquinone. Listed as particularly preferred compounds are those represented by General Formula II described in Japanese Patent Application Open to Public Inspection No. 4-133056, which include compounds II-1 through II-14 described on pages 14 and 15 and compound 1 described on page 17 of the aforesaid patent publication.
It is preferable that by adding UV absorbers to the silver halide light-sensitive color photographic material of the present invention, static fog is minimized and the lightfastness of dye images is enhanced. Listed as preferred UV absorbers are benzortiazoles. Listed as particularly preferred compounds are those represented by General Formula III-3 described in Japanese Patent Application Open to Public Inspection No. 1-250944, the compounds represented by General Formula III described in Japanese Patent Application Open to Public Inspection No. 64-66646, UV-1L through UV-27L described in Japanese Patent Application Open to Public Inspection No. 63-187240, the compounds represented by General Formula I described in Japanese Patent Application Open to Public Inspection No. 4-1633, and the compounds represented by General Formulas (I) and (II) described in Japanese Patent Application Open to Public Inspection No. 5-165144.
It is advantageous to use gelatin as a binder in the silver halide light-sensitive color photographic materials of the present invention. If desired, it is possible to use other gelatin such as gelatin derivatives, graft polymers of gelatin with other polymers, proteins other than gelatin, sugar derivatives, cellulose derivatives, and hydrophilic colloid of synthetic hydrophilic polymers such as homopolymers or copolymers.
It is preferable that employed as a hardener of these binders are vinylsulfone type hardeners and chlorotriazine hardeners individually or in combination. It is preferable to employ t he compounds described in Japanese Patent Application Open to Public Inspection Nos. 61-249054 and 61-245153. In order to minimize an increase in mildew and bacteria, which adversely affect photographic performance as well as image retaining properties, it is preferable to add colloid layers antiseptics and mildewcides described in Japanese Patent Application Open to Public Inspection No. 3-157646. Further, in order to enhance physical properties of light-sensitive materials or the surface of processed samples, it is preferable that slipping agents and matting agents are added which are described in Japanese Patent Application Open to Public Inspection Nos. 6-118543 and 2-73250.
The supports employed to prepare the light-sensitive materials of the present invention may be comprised of any of a number of materials, and include paper coated with polyethylene or polyethylene terephthalate, paper supports comprised of natural pulp or synthetic pulp, vinyl chloride sheets, polypropylene or polyethylene terephthalate supports which may comprise white pigments, and baryta paper. Of these, supports are preferred which comprise a base paper having on both sides water resistant resinous coating layers. Preferred as water resistant resins are polyethylene and polyethylene terephthalate, or copolymers thereof.
White pigments employed in supports include inorganic and/or organic white pigments. Of these, inorganic white pigments are preferably employed. Listed as inorganic white pigments are, for example, sulfates of alkaline earth metals such as barium sulfate, carbonates of alkaline earth metals such as calcium carbonate, silica such as fine silicate powders and synthetic silicates, calcium silicate, alumina, alumina hydrates, titanium oxide, zinc oxide, talc, and clay. Of these, white pigments, barium sulfate and titanium oxide are preferred.
In order to improve sharpness, the proportion of white pigments incorporated in the water resistant resinous layer on the surface of a support is preferably at least 13 percent by weight, and is more preferably at least 15 percent.
In the paper supports employed in the light-sensitive materials of the present invention, it is possible to determine the degree of dispersion of white pigment in the water resistant resinous layer, employing the method described in Japanese Patent Application Open to Public Inspection No. 2-28640. When employing this method, the degree of dispersion of a white pigment is preferably at most 0.20 in terms of the variation coefficient described in the aforesaid patent publication, and is more preferably at most 0.15.
Further, the central surface mean roughness (SRa) of supports is preferably at most 0.15 xcexcm, and is more preferably at most 0.12 xcexcm, resulting in effects for enhanced glossiness. Further, in order to regulate the balance of spectral reflection density of the white portion after processing so as to enhance whiteness, it is preferable that a minute amount of bluing agents, and red providing agents such as ultramarine and oil-soluble dyes, or optical brightening agents is added into water-resistant resins comprising white pigments of the reflection support and coated hydrophilic colloid layers.
In the light-sensitive materials of the present invention, if desired, the support surface may be subjected to corona discharge, UV irradiation, or a flaming treatment, and subsequently, each of the photographic constitution layers may be applied directly onto a support or via sublayer(s) (one or more layers to enhance the adhesion properties of the support surface, antistatic properties, dimensional stability, abrasion resistance, hardness, antihalation properties, friction characteristics and/or other characteristics) onto a support.
During coating of light-sensitive photographic materials employing silver halide emulsions, viscosity increasing agents may be employed to enhance coatability. As coating methods, extrusion coating as well as curtain coating, capable of simultaneously coating at least two layers, is particularly useful.
Photographic images are formed on the light-sensitive materials of the present invention as follows. An image recorded on a negative film may be optically focused on a light-sensitive material which is used to make prints and then printed; after temporarily converting an image into digital information, an image is formed on a CRT (cathode ray tube) and the resulting image is focused on a light-sensitive material which is used to make prints and then printed; or printing may be carried out through scanning based on digital information, under varying laser beam intensity.
The present invention is preferably applied to light-sensitive materials which do not comprise developing agents in their interior, and particularly to light-sensitive materials which form images for direct viewing. Listed as such light-sensitive materials are, for example, color paper, color reversal paper, positive image forming light-sensitive materials, light-sensitive materials for display, and light-sensitive materials for color proofs. The application to light-sensitive materials comprising a reflection support is particularly preferred.
Employed as aromatic primary amine developing agents may be any of the compounds known in the art. Listed as examples of such compounds are those described below:
CD-1: N,N-diethyl-p-phenylenediamine
CD-2: 2-amino-5-diethylaminotoluene
CD-3: 2-amino-5-(N-ethyl-N-laurylamino)toluene
CD-4: 4-(N-ethyl-N-(xcex2-hydroxyethyl)amino)aniline
CD-5: 2-methyl-4-(N-ethyl-N-(xcex2-hydroxyethyl)amino)aniline
CD-6: 4-amino-3-methyl-N-(xcex2-(methanesufonamido)ethyl)aniline
CD-7: N-(2-amino-5-diethylaminophnylethyl)methanesulfoneamide
CD-8: N,N-dimethyl-p-phenylenediamine
CD-9: 4-amino-3-methyl-N-ethyl-N-metjoxyethylaniline
CD-10: 4-amino-3-methyl-N-ethyl-N-(xcex2-ethoxyethyl) aniline
CD-11: 4-amino-3-methyl-N-ethyl-N-(xcex3-hydoxypropyl)aniline
In the present invention, the aforesaid color developing agents are employed in the optional pH range. However, from the viewpoint of quick processing, the pH is preferably in the range of 9.5 to 13.0, and is more preferably in the range of 9.8 to 12.0.
The temperature of color development is preferably from 35 to 70xc2x0 C. It is preferable to increase the temperature to reduce the processing time. On the other hand, from the viewpoint of stability of the processing solution, it is preferable to maintain the temperature at a relatively low level. It is therefore preferable to carry out processing between 37 and 60xc2x0 C.
Color development is commonly carried out over approximately 3 minutes 30 seconds. However, in the present invention, color development is preferably carried out within 40 seconds, and is more preferably carried out within 25 seconds.
It is possible to add known developer component compounds to the color developing solution in addition to the aforesaid color developing agents. Generally employed are alkali agents exhibiting a pH buffering action, chloride ions, development restrainers such as benzortiazoles, preserving agents, and chelating agents.
The light-sensitive materials of the present invention are bleached and fixed after color development. The bleaching may be simultaneously carried out with the fixing. Generally, washing is carried out after the fixing. Further, instead of washing, a stabilization process may be carried out. Employed as photographic processors, in which the light-sensitive materials of the present invention are subjected to photographic processing, may be a roller transport type processor in which light-sensitive materials are transported while interposed between rollers arranged in processing tanks, and an endless belt type processor in which light-sensitive materials are fixed onto a belt and transported. Further, the following systems may also be employed: a system in which processing tanks are shaped so as to form a slit and while supplying processing solution to processing tanks, light-sensitive materials are transported; a spray system in which processing solutions are sprayed; a web system in which light-sensitive materials are brought into contact with bodies impregnated with processing solutions; and a system which utilizes viscous processing solutions. When a large amount of light-sensitive materials are processed, a running process is usually carried out employing an automatic processor. In such a case, the less the replenishment rate of a replenisher, the better. From the viewpoint of environmental protection, the most preferable processing embodiment is that as a replenishment method, processing agents are added in the form of tablets, and the method described in Kokai Gihou (Japanese Technical Disclosure) No. 94-16935 is most preferred.